and motion in non-uniformity; and the cause of the non-uniform nature lies in inequality. Now we have explained the origin of inequalityCf. 53 C ff.: the varying shapes and sizes of the primary triangles account for the “inequality.”; but we have not declared how it is that these bodies are not separated according to their several Kinds, and cease not from their motion and passage one through another. Wherefore, we shall once more expound the matter as follows. The revolution of the All, since it comprehends the Kinds, compresses them all, seeing that it is circular and tends naturally to come together to itselfi.e., exerts a centripetal force. For this “compression” cf. Emped. Frag. 185 Τιτὰν ἠδ᾽ αἰθὴρ σφίγγων περὶ κύκλον ἅπαντα.; and thus it suffers no void place to be left.